FD&C Yellow No. 6: Sunset Yellow Food Dye

FD&C Yellow no. 6 is a synthetic food colorant (food dye, food coloring) with a reddish-yellow hue used to color beverages, cereals bakery goods, confections, and ice cream. It is also used to color dietary supplements, oral and externally applied drugs, cosmetics, and as a pigment in printing inks. This dye is supplied in the form of orange-red crystals. Its common name is sunset yellow FCF and its molecular formula is C16H10N2Na2O7S2. It is permanently listed by the FDA as a certified food color additive.

Large-scale production of sunset yellow started in the U.S. in the 1920’s and it is now used worldwide. The colorant is an azo dye. Azo compounds are formed from arenediazonium ions reacting with highly reactive aromatic compounds, in what is called a diazo coupling reaction. Sunset yellow is one of the most widely used colorants in foods.

Yellow #6 is made in one of three ways:

By diazotizing 4-aminobenzenesulfonic acid using hydrochloric acid and sodium nitrite or sulfuric acid and sodium nitrite. The diazo compound is then coupled with 6-hydroxy-2-naphthalene-sulfonic acid. The dye is isolated as the sodium salt and dried. The trisodium salt of 3-hydroxy-4-[(4- sulfophenyl)azo]-2,7-naphthalenedisulfonic acid may be blended with the principal color.

Safety

Animal studies, mostly on mice, have provided no evidence that FC and C Yellow number 6 is carcinogenic or genotoxic. A known contaminant of yellow #6 called Sudan I (1-(phenylazo)-2-naphthalenol), itself a yellow-orange dye banned in many countries, has been shown to be genotoxic and carcinogenic in studies, so the level of this contaminant needs to be as low as possible. Similar to the many names for the dye given above, this contaminant goes by many different names and so is a source of confusion for legislation and manufacturing. Depending on the legislation in your country amounts of allowed impurities, including Sudan I, may vary, and so the adverse effects of the dye cannot be accurately predicted.

It may cause allergic or pseudo-allergic reactions which may be worse in people with asthma or urticaria. Cross-sensitivity with sulphanilic acid has been suggested to be the cause of this allergic response. These reactions are extremely rare. Reactions to food dyes are not IgE (true allergic type) reactions, so they are sometimes classified as food intolerances rather than food allergies.

Do not confuse these reactions with the hive-like reactions to FD%C Yellow No. 5, also extremely rare, since Yellow No. 5 must be identified on product ingredient lines, so that those sensitive can avoid it. Also, despite the number 5 being present in some of the synonyms listed above, FD&C Yellow No. 6 and No. 5 are two different colorants.

Although moderate amounts of this or any other presently approved synthetic food dye is not likely to be harmful to health, it is best to avoid foods that use synthetic dyes whenever possible.

FDA Regulation

As one of nine certified food color additives, sunset yellow must meet high standards of purity and is tested by the FDA for compliance with its standards. The 1960 Color Additive Amendment to the FD&C Act originally listed nine synthetic colorants as permitted in food and drugs. This amendment was enacted after many children became ill in 1950 from eating an orange Halloween candy containing 1-2% FD&C Orange No. 1. There is no GRAS exemption for synthetic color additives. The Federal Food, Drug, and Cosmetic Act (FD&C Act) provides that a substance that imparts color is a color additive (generally recognized as safe) and they are subject to premarket approval requirements unless the substance is used solely for a purpose other than coloring.

Controversy

Professor Jim Stevenson from Southampton University made a study into the effects of artificial food dyes on hyperactivity in children. Sunset Yellow (yellow no. 6) was among those tested (along with FD&C Yellow No. 5) and some food preservatives. The report concluded that there may be a connection between consumption of certain combinations of food colorants and preservatives and increased hyperactive behavior in children. The British Food Standards Agency called for these additives to be voluntarily phased out by 2009, an effort that is still ongoing. The Center for Science in the Public Interest has petitioned the FDA that all synthetic food dyes be banned.